The present invention relates to the use of Echinacea as a cancer chemopreventive agent to block the formation of and to detoxify cancer-causing agents, or carcinogens. More particularly, the present invention relates to the induction of phase II enzymes by Echinacea, and specifically by lipid-soluble fractions isolated from Echinacea. The present invention relates to the use of lipid-soluble fractions isolated from Echinacea as nutritional supplements. The present invention also contemplates a novel method of extracting the desired lipid-soluble fractions from Echinacea. 
Phase II enzymes are involved in the detoxification of cancer-causing agents by converting carcinogenic substances into products that are no longer harmful. Unexpectedly, certain fractions of Echinacea, particularly the lipid-soluble fractions, show a greater induction of phase II enzymes than other fractions. It is desirable to use these lipid-soluble fractions as a dietary supplement because they are the most potent and can yield the greatest benefit for cancer prevention.
Echinacea contains numerous active phytochemicals that have immunomodulatory and other beneficial activities. There is a long tradition of the use of Echinacea preparations in the adjuvant therapy of inflammations (see, Tragni et al., Evidence from two classic irritation tests for an anti-inflammatory action of a natural extract, Echinacea B., Food Chem. Toxicol., 23(2): 317–319 (1985); and Facino et al., Direct characterization of caffeoyl esters with antihyaluronidase activity in crude extracts from Echinacea angustifolia roots by fast atom bombardment tandem mass spectrometry, Farmaco, 48(10): 1447–1461 (1993)), skin damage (see, Facino et al., Echinacoside and caffeoyl conjugates protect collagen from free radical-induced degradation: a potential use of Echinacea extracts in the prevention of skin photodamage, Planta Med., 61(6): 510–514 (1995)), and, more typically, infections (see, Steinmuller et al., Polysaccharides isolated from plant cell cultures of Echinacea purpurea enhance the resistance of immunosuppressed mice against systemic infections with Candida albicans and Listeria monocytogenes, Int. J. Immunopharmacol., 15(5): 605–614 (1993)). The Echinacea plant is a popular herbal immunostimulant. The ability of Echinacea to stimulate the immune system in a nonspecific manner is exemplified in the enhancement of phagocytosis seen in cells treated with Echinacea (see, Sun et al., The American coneflower: a prophylactic role involving nonspecific immunity, J. Altern. Complement Med., 5(5): 437–446 (1999)). Echinacea's immunomodulatory activity has been attributed to various actives, including alkylamides, phenolics, polysaccharides, alkaloids, glycoproteins, and flavonoids (see, Bauer, R. and Wagner, H., Echinacea species as potential immunostimulatory drugs, in Economic and Medicinal Plant Research, Ch. 8, p. 253, Wagner, H. and Farnsworth, N. R. (Editors), Academic Press Limited, New York, N.Y., (1991)).
Phase II enzymes are a class of enzymes that detoxify cancer-causing agents and protect cells against neoplasia and mutagenesis. Phase II enzymes are thought to act by detoxifying highly reactive intermediates of carcinogens activated by Phase I enzymes. Phase II enzymes include NAD(P)H quinone reductase (quinone reductase or QR) and glutathione S-transferases (GST). The consumption of vegetables, especially crucifers, such as broccoli (Zhang et al., A major inducer of anticarcinogenic protective enzymes from broccoli: isolation and elucidation of structure, Proc. Natl. Acad. Sci., USA., 89(6): 2399–2403 (1992)) and broccoli sprouts (Fahey, et al., Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens, Proc. Natl. Acad. Sci. USA, 94: 10367–10372 (1997)) has been associated with the induction of phase II enzymes. Broccoli contains high levels of the compound sulforaphane which has been shown to be a potent inducer of phase II enzymes.
The ability of a compound or compounds to induce phase II enzymes can be measured by monitoring the increase in the activity of the phase II enzyme quinone reductase (QR). The induction of quinone reductase can be tested using a cell culture system similar to that developed by Prochaska et al. (Prochaska, H. J. and Santamaria, A. B., Direct Measurement of NAD(P)H:quinone reductase from cells cultured in microtiter wells: a screening assay for anticarcinogenic enzyme inducers, Anal. Biochem., 169(2): 328–336 (1988)) which is incorporated herein by reference. This system measures the elevation of quinone reductase, thus detecting the potency of the phase II enzyme inducers.